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KPA-1500 Fan Noise

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KPA-1500 Fan Noise

Just thought I would add a few thoughts as far as the fan noise.

I'm not certain a YouTube piece would help, but perhaps personal observations might.

First, via the menu, you can select the minimum fan speed, 0-5. Of course, the fan speed will go up with the Amp temperature.

These are my personal observations:

0-Nothing
1-Barely perceptible
2-Acceptable fan noise, even for SSB operating. Low pitched whine
3-The noise and the pitch of the whine is past the acceptable point. Even a very directional mic will probably pick up the noise. This is where Noise Cancelling headphones would start to help.
4-Louder and higher pitched whine
5-Very loud and higher pitched whine

So, the fan noise becomes particularly bothersome on level 3 and above. If you are doing CW and/or Digital, the noise will only be a factor with the operator. On SSB, the noise will probably be noticeable on the air. However, the SSB duty cycle may not require higher fan speeds. Those who have been active in contests will probably know that answer.

Rich, if fan noise is going to be that strong a factor, perhaps you should be looking at tube amps instead. Personally, if I found the KPA-1500 fan noise excessive in the future, I would plan on moving it off my desk or remoting it rather than replacing it. It's integration with the K3 would be very hard to give up.

’73 de JIM N2ZZ
#106

-----Original Message-----
From: [hidden email] [mailto:[hidden email]] On Behalf Of Dr. William J. Schmidt
Sent: Friday, June 01, 2018 8:59 PM
To: 'Elecraft Reflector'
Subject: Re: [Elecraft] KPA-1500 Fan Noise - YouTube ?

So just a bit of thermodynamics... if the input to any amplifier is 1500 watts and it is 50% efficient, since energy is conserved, 750 watts will come out in another form.. and in this case it's heat. Doesn't matter what the converter is (transistor, tube, resistor, etc.). It all behaves the same. Need to get rid of 750 watts of heat. The only difference may be the way the heat is taken away of the converter... convection (heat sink), forced convection (heat skin plus fan), liquid convection (water cooled heat sink). The poison is the heat removal device not the converter.

Dr. William J. Schmidt - K9HZ J68HZ 8P6HK ZF2HZ PJ4/K9HZ VP5/K9HZ PJ2/K9HZ

Owner - Operator
Big Signal Ranch – K9ZC
Staunton, Illinois

Owner – Operator
Villa Grand Piton – J68HZ
Soufriere, St. Lucia W.I.
Rent it: www.VillaGrandPiton.com
Like us on Facebook!

Moderator – North American QRO Group at Groups.IO.

email: [hidden email]

-----Original Message-----
From: [hidden email] [mailto:[hidden email]] On Behalf Of Bill Stravinsky via Elecraft
Sent: Friday, June 1, 2018 7:33 PM
To: Elecraft Reflector <[hidden email]>
Subject: Re: [Elecraft] KPA-1500 Fan Noise - YouTube ?

Rich

You pretty much hit the nail on the head about solid state amps. As they say there's no free lunch. Solid state has made great strides in high power ampsbut its still solid state and a p/n junction or some form thereof. 1500 watts of heat in those junctions has to be cooled down or it won't be long before it needsnew parts.
Depending on your operating habits (contesting, casual, or whatever) there will be varying degrees of fan noise. The higher the duty cycle the higher thefan requirements. Pick your poison, a small light weight amp easy to move around or one you need a fork lift to pick up. I prefer tube amps for a few reasonsand have the Acom 2000a (and an Alpha 89 that now sits in the living room temporarily) but I'm still glad I got the kpa1500 at least so far.
The kpa sits nicely on top of the Acom without causing the table they sit on to crash to the floor in pieces, hi. I'm surprised nobody has made a you tube ofthe amp in operation actually. But there are only just over 200 of the new amps out there. Good luck with your investigation, Rich.
BillK3WJV

On Friday, June 1, 2018, 8:00:29 PM EDT, Richard Thorne <[hidden email]> wrote:

This fan noise issue has me concerned to the point that I’m considering cancelling my order.

While the amp won’t be on my operating desk, it will be on a rack next to my operating desk. Remoting the amp is not an option. Quite frankly I have no interest in remoting the amp.

Is there anyone out there that has a KPA-1500 willing to post a YouTube video so we can hear the fan in action and judge the noise for ourselves?

From the research I’ve done it appears that if you want a solid state amp, regardless of make, you need to be prepared for fan noise.

Thanks

Rich - N5ZC

Sent from my iPhone
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John Perlick

Re: KPA-1500 Fan Noise

Bill Schmidt is right--you have to get rid of a bunch of heat--no matter what device you are using to amplify (tubes, transistors, or magic). The amplifying device must dissipate considerable heat because we are running Class AB and because of all electronic devices are naturally lossy.

Remember that this heat is generated not only in the RF transistors, but also in the power supplies, bias circuits, lights, etc. There are lots of heat sources in every amplifier.

I can honestly say that my KPA1500 is considerably quieter than the Expert 2KFA that I just sold and I would have to say it is quieter than my old Alpha 87A. I do operate it at full 1.5 KW output but I suspect my duty cycle on CW has not caused it to so how that the fans max out. Same for the 2KFA, but even at low speeds, it was far noisier. And, the 2KFA has REALLY loud T/R relays!
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Elecraft mailing list

Re: KPA-1500 Fan Noise

I don’t have a dog in this fight - someone who spends half the year (the half with all the good contests) in a Florida condo is not a candidate for buying amps. But might water cooling be a possibility? As in a heat sink that sits in water, with appropriate thermal shutoff if the water/amp get too warm?

And when that happens, get fresh cool water.

73 - Jim K8MR

> On Jun 2, 2018, at 4:06 AM, John Perlick <[hidden email]> wrote:
>
> Bill Schmidt is right--you have to get rid of a bunch of heat--no matter what device you are using to amplify (tubes, transistors, or magic). The amplifying device must dissipate considerable heat because we are running Class AB and because of all electronic devices are naturally lossy.
>
> Remember that this heat is generated not only in the RF transistors, but also in the power supplies, bias circuits, lights, etc. There are lots of heat sources in every amplifier.
>
> I can honestly say that my KPA1500 is considerably quieter than the Expert 2KFA that I just sold and I would have to say it is quieter than my old Alpha 87A. I do operate it at full 1.5 KW output but I suspect my duty cycle on CW has not caused it to so how that the fans max out. Same for the 2KFA, but even at low speeds, it was far noisier. And, the 2KFA has REALLY loud T/R relays!
> ______________________________________________________________
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WILLIE BABER

Re: KPA-1500 Fan Noise

In reply to this post by Elecraft mailing list

I have a Lunar-LInk System 72 (432 mhz) Amplifier using a pair of 3cx800 (perfectly designed by K1FO SK), in a cubic package that may actually be smaller than the KPA1500 (of course the power supply is external, and the blower and T/R relays are attached to the back of the amp). I had a choice of Dayton blowers, one for ssb/cw (60 CFM if I recall correctly) and one for moon-bounce or key-down modes (100 CFM, I think). I got the 100 CFM blower, anyway the one that moves more air; 100 CFM makes a lot more noise!

The only discussion about blower noise was to provide this choice (sometime after I got my unit it became possible to purchase the 100 CFM blower but it ran at two speeds).

I imagine that levels 4, and 5 are related to key down modes in KPA1500, and maybe level 3 as well. I suppose one can reduce fan or blower noise to some extent by paying attention to relevant details about fan and noise but all significant variables held constant (like the size of the amp and the power output), there is no free lunch (as usual), solid-state or not.

I recall the conduction cooled amps (no fan, no noise), one by Henry Radio (2 x 8873) and another by Heathkit (one 8873). You had to reduce power significantly for key-down modes, and neither amp made 1500 watts output rtty key-down (1000 watts cw for the Henry--but of course this was before the current maximum legal power output). Still, how long you could hold down the key depended upon ventilation of the amplifier. Heathkit recommended only 200 watts output for rtty. I imagine guys placed fans (making some noise) near the heatsinks!

So, to put this into perspective, how long the key can be held down using kpa1500 at 1500 watts output power may have something to do with fan speed number five!

If you want "almost silent high power", then try running kpa1500 at 500 watts output (about like a conduction cooled amp--but don't hold that key down too long without ventilation).

73, Will. wj9b

CWops #1085
CWA Advisor levels II and III
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CWops #1085
CWA Advisor levels II and III
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--------------------------------------------
On Sat, 6/2/18, Jim via Elecraft <[hidden email]> wrote:

Subject: Re: [Elecraft] KPA-1500 Fan Noise
To: "John Perlick" <[hidden email]>
Cc: "[hidden email]" <[hidden email]>
Date: Saturday, June 2, 2018, 6:20 AM

I don’t have a dog in this
fight - someone who spends half the year (the half with all
the good contests) in a Florida condo is not a candidate for
buying amps. But might water cooling be a possibility? As in
a heat sink that sits in water, with appropriate thermal
shutoff if the water/amp get too warm?

And when that happens, get fresh cool water.

73 -
Jim K8MR

> On Jun 2, 2018, at 4:06 AM, John Perlick
<[hidden email]>
wrote:
>
> Bill
Schmidt is right--you have to get rid of a bunch of heat--no
matter what device you are using to amplify (tubes,
transistors, or magic). The amplifying device must dissipate
considerable heat because we are running Class AB and
because of all electronic devices are naturally lossy.
>
> Remember that this
heat is generated not only in the RF transistors, but also
in the power supplies, bias circuits, lights, etc. There
are lots of heat sources in every amplifier.
>
> I can honestly say
that my KPA1500 is considerably quieter than the Expert 2KFA
that I just sold and I would have to say it is quieter than
my old Alpha 87A. I do operate it at full 1.5 KW output
but I suspect my duty cycle on CW has not caused it to so
how that the fans max out. Same for the 2KFA, but even at
low speeds, it was far noisier. And, the 2KFA has REALLY
loud T/R relays!
>
______________________________________________________________
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>
Home: http://mailman.qth.net/mailman/listinfo/elecraft
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http://www.qsl.net
>
Please help support this email list: http://www.qsl.net/donate.html
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Jeff Griffin

KPA500 and K3 SWR meters disagree

I recently brought my KPA/KAT500 north for the summer and hooked up to my trapped multiband fan dipole that I use here in NJ. I leave my K3 here for remote use and use the amp at my winter home in Florida to use with my Flex 6500 with a Steppir Vertical antenna without the KAT500 tuner. When I got up here I installed the KIO3B option. The install went well with no issues, all looked good so I connected the K3, P3, KAT500, and KPA500 with the Elecraft provided cable set like I do every year.

The issue I'm having is an SWR difference between the KAT500 and the K3. For example if I use the K3's internal tuner I can on a chosen frequency achieve an SWR of 1/1. I the put the internal K3 tuner in bypass mode and take the KAT500 out of bypass and set to auto. I then use the xmit button on the K3 to create a tune signal to be sent to the KAT500. The K3 then shows a 1/1, the KAT500 about the same but the KPA500 which is in STBY mode shows around 3/1. What this causes to happen is the Amp will fault out if I try to use any power output. If I check the antenna with a trusted SWR meter I see 1.3/1 at the frequency of use. I upgraded the firmware in all the devices in use, I also did a reset of the KAT's stored frequencies memory, and checked both the amp and tuner with the utility programs. I'm going to call Elecraft on Monday, anyone have any ideas in the meantime I can try?

73 Jeff kb2m

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Les Peters

Re: KPA-1500 Fan Noise

In reply to this post by Elecraft mailing list

Jim I agree with your personal observations. I run some high duty cycle modes so I notice the fans kicking into speed 3 a lot when the PA temp gets to 68-70 degrees. That setting does a good job of reducing the temp and keeping it from climbing past 73 degrees. I've changed my min fan speed threshold from 0 to 1 to also help. As you have pointed out 1 is barely perceptible and this helps to reduce the amount of time that fan speeds are on 2+.

I'd like to have more separation between the K3S and the KPA1500 RF deck to further distance any noise but the KPAK3AUX cable is only about five feet long, it would be great if that were more like ten feet. Since the cable pin out is straight thru I would imagine a DB15 VGA M-F extension cable would suffice? That would put the potential fan noise even further away but have the RF deck still plenty close enough to view.

Les, N1SV

#113

> Date: Fri, 1 Jun 2018 23:07:20 -0400
> From: "James F. Boehner MD"
> To: "'Elecraft Reflector'"
> Subject: [Elecraft] KPA-1500 Fan Noise
> Message-ID: <002901d3fa1e$d39e0db0$7ada2910$@yahoo.com mailto:002901d3fa1e$d39e0db0$7ada2910$@yahoo.com >
> Content-Type: text/plain; charset="utf-8"
>
> Just thought I would add a few thoughts as far as the fan noise.
>
> I'm not certain a YouTube piece would help, but perhaps personal observations might.
>
> First, via the menu, you can select the minimum fan speed, 0-5. Of course, the fan speed will go up with the Amp temperature.
>
> These are my personal observations:
>
> 0-Nothing
> 1-Barely perceptible
> 2-Acceptable fan noise, even for SSB operating. Low pitched whine
> 3-The noise and the pitch of the whine is past the acceptable point. Even a very directional mic will probably pick up the noise. This is where Noise Cancelling headphones would start to help.
> 4-Louder and higher pitched whine
> 5-Very loud and higher pitched whine
>
> So, the fan noise becomes particularly bothersome on level 3 and above. If you are doing CW and/or Digital, the noise will only be a factor with the operator. On SSB, the noise will probably be noticeable on the air. However, the SSB duty cycle may not require higher fan speeds. Those who have been active in contests will probably know that answer.
>
> Rich, if fan noise is going to be that strong a factor, perhaps you should be looking at tube amps instead. Personally, if I found the KPA-1500 fan noise excessive in the future, I would plan on moving it off my desk or remoting it rather than replacing it. It's integration with the K3 would be very hard to give up.
>
>
> ?73 de JIM N2ZZ
> #106
> **************************
>

Don Wilhelm

Re: KPA500 and K3 SWR meters disagree

In reply to this post by Jeff Griffin

Jeff,

Check the coax between the KPA500 and the KAT500. Make certain the
connectors are tight. Replace with a different coax if you have one.

You can always do a check on the KPA500 wattmeter by connecting a dummy
load to the KPA500 (no tuner).

73,
Don W3FPR

On 6/2/2018 11:48 AM, jeff griffin wrote:

> I recently brought my KPA/KAT500 north for the summer and hooked up to my trapped multiband fan dipole that I use here in NJ. I leave my K3 here for remote use and use the amp at my winter home in Florida to use with my Flex 6500 with a Steppir Vertical antenna without the KAT500 tuner. When I got up here I installed the KIO3B option. The install went well with no issues, all looked good so I connected the K3, P3, KAT500, and KPA500 with the Elecraft provided cable set like I do every year.
>
> The issue I'm having is an SWR difference between the KAT500 and the K3. For example if I use the K3's internal tuner I can on a chosen frequency achieve an SWR of 1/1. I the put the internal K3 tuner in bypass mode and take the KAT500 out of bypass and set to auto. I then use the xmit button on the K3 to create a tune signal to be sent to the KAT500. The K3 then shows a 1/1, the KAT500 about the same but the KPA500 which is in STBY mode shows around 3/1. What this causes to happen is the Amp will fault out if I try to use any power output. If I check the antenna with a trusted SWR meter I see 1.3/1 at the frequency of use. I upgraded the firmware in all the devices in use, I also did a reset of the KAT's stored frequencies memory, and checked both the amp and tuner with the utility programs. I'm going to call Elecraft on Monday, anyone have any ideas in the meantime I can try?
>
> 73 Jeff kb2m
>
> ______________________________________________________________
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>

Don Wilhelm

Re: KPA-1500 Fan Noise

In reply to this post by Les Peters

Les,

A VGA extension will NOT do the job. Get a cable with all 15 pins
connected straight through.

73,
Don W3FPR

On 6/2/2018 12:07 PM, Les Peters wrote:

> Jim I agree with your personal observations. I run some high duty cycle modes so I notice the fans kicking into speed 3 a lot when the PA temp gets to 68-70 degrees. That setting does a good job of reducing the temp and keeping it from climbing past 73 degrees. I've changed my min fan speed threshold from 0 to 1 to also help. As you have pointed out 1 is barely perceptible and this helps to reduce the amount of time that fan speeds are on 2+.
>
>
> I'd like to have more separation between the K3S and the KPA1500 RF deck to further distance any noise but the KPAK3AUX cable is only about five feet long, it would be great if that were more like ten feet. Since the cable pin out is straight thru I would imagine a DB15 VGA M-F extension cable would suffice? That would put the potential fan noise even further away but have the RF deck still plenty close enough to view.
>
>
> Les, N1SV
>
> #113
>
>> Date: Fri, 1 Jun 2018 23:07:20 -0400
>> From: "James F. Boehner MD"
>> To: "'Elecraft Reflector'"
>> Subject: [Elecraft] KPA-1500 Fan Noise
>> Message-ID: <002901d3fa1e$d39e0db0$7ada2910$@yahoo.com mailto:002901d3fa1e$d39e0db0$7ada2910$@yahoo.com >
>> Content-Type: text/plain; charset="utf-8"
>>
>> Just thought I would add a few thoughts as far as the fan noise.
>>
>> I'm not certain a YouTube piece would help, but perhaps personal observations might.
>>
>> First, via the menu, you can select the minimum fan speed, 0-5. Of course, the fan speed will go up with the Amp temperature.
>>
>> These are my personal observations:
>>
>> 0-Nothing
>> 1-Barely perceptible
>> 2-Acceptable fan noise, even for SSB operating. Low pitched whine
>> 3-The noise and the pitch of the whine is past the acceptable point. Even a very directional mic will probably pick up the noise. This is where Noise Cancelling headphones would start to help.
>> 4-Louder and higher pitched whine
>> 5-Very loud and higher pitched whine
>>
>> So, the fan noise becomes particularly bothersome on level 3 and above. If you are doing CW and/or Digital, the noise will only be a factor with the operator. On SSB, the noise will probably be noticeable on the air. However, the SSB duty cycle may not require higher fan speeds. Those who have been active in contests will probably know that answer.
>>
>> Rich, if fan noise is going to be that strong a factor, perhaps you should be looking at tube amps instead. Personally, if I found the KPA-1500 fan noise excessive in the future, I would plan on moving it off my desk or remoting it rather than replacing it. It's integration with the K3 would be very hard to give up.
>>
>>
>> ?73 de JIM N2ZZ
>> #106
>> **************************
>>
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k6dgw

Re: KPA-1500 Fan Noise

In reply to this post by John Perlick

Yes John, and it turns out to be a fairly simple equation if you make a
few assumptions. Around 1958 or so and a student [sophomore], I spent
the summer with a small crew building KPFK on Mt. Wilson in Los
Angeles. The TX was almost totally homebrew [REL serrasoid exciter],
with 4 4-1000A's in the PA [4 parallel class-C 4-1000A's at 90.7 Mcs was
a bit of a challenge [:-) ]. About to return to school, I was reviewing
the physics I'd supposedly learned the previous year and realized I
should be able to calculate the efficiency of the PA from the smattering
of thermodynamics I knew. Tx engineers don't have much to do until
something breaks.

I knew the pressure difference between the air inlet and the exhaust
[quite small, there was a differential manometer], the filaments
dissipated 600 W, nearly all in heat, and I knew the temp difference
between the gozinta and gozouta air so I could calculate the mass of the
air moving per unit time or so I thought. Then, with the PA on and
stable [3.5 A @ ~5.8 KV], I could do it again only this time calculate
the power lost to heat the air. Subtract the 600 W from the filaments,
and I got 69.4%. I assumed the air was heated at constant pressure, my
calculus hadn't progressed far enough to do otherwise.

After I went back to school, they finally measured the efficiency on a
2-stage oil/water cooled dummy load and called me and said they got
71.3%. If it doesn't go up the 3 1/8" hardline, it comes out as heat
... somewhere. There's only two options.

I'm a little surprised at the obsession with fan noise ... I'd like to
hear about how much more DX everyone is working with a KPA1500.

73,

Fred ["Skip"] K6DGW
Sparks NV DM09dn
Washoe County

On 6/2/2018 1:06 AM, John Perlick wrote:
> Bill Schmidt is right--you have to get rid of a bunch of heat--no matter what device you are using to amplify (tubes, transistors, or magic). The amplifying device must dissipate considerable heat because we are running Class AB and because of all electronic devices are naturally lossy.
>
>

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Jack Brindle-2

Re: KPA500 and K3 SWR meters disagree

In reply to this post by Jeff Griffin

Jeff;

Do I understand that for the first test you are driving the antenna through the KPA500 and KAT500 (with KAT500 in bypass)? If so, it makes a lot of sense that you will see different SWR. The KPA and KAT are providing a completely different load for the K3. The better test is to feed the antenna directly from the K3 without the KPA and KAT in-line. I would expect you to see a closer match at that point, although I doubt they will ever be identical due to the differences in the directional couplers in the K3 vs the KAT500 (and KPA500 for that matter).

Jack, W6FB

> On Jun 2, 2018, at 8:48 AM, jeff griffin <[hidden email]> wrote:
>
> I recently brought my KPA/KAT500 north for the summer and hooked up to my trapped multiband fan dipole that I use here in NJ. I leave my K3 here for remote use and use the amp at my winter home in Florida to use with my Flex 6500 with a Steppir Vertical antenna without the KAT500 tuner. When I got up here I installed the KIO3B option. The install went well with no issues, all looked good so I connected the K3, P3, KAT500, and KPA500 with the Elecraft provided cable set like I do every year.
>
> The issue I'm having is an SWR difference between the KAT500 and the K3. For example if I use the K3's internal tuner I can on a chosen frequency achieve an SWR of 1/1. I the put the internal K3 tuner in bypass mode and take the KAT500 out of bypass and set to auto. I then use the xmit button on the K3 to create a tune signal to be sent to the KAT500. The K3 then shows a 1/1, the KAT500 about the same but the KPA500 which is in STBY mode shows around 3/1. What this causes to happen is the Amp will fault out if I try to use any power output. If I check the antenna with a trusted SWR meter I see 1.3/1 at the frequency of use. I upgraded the firmware in all the devices in use, I also did a reset of the KAT's stored frequencies memory, and checked both the amp and tuner with the utility programs. I'm going to call Elecraft on Monday, anyone have any ideas in the meantime I can try?
>
> 73 Jeff kb2m
>
> ______________________________________________________________
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Jeff Griffin

Re: KPA500 and K3 SWR meters disagree

In reply to this post by Don Wilhelm

Thanks for the reply Don. Tried that and didn't work, still have the SWR issue. Tried the amp on a resonant frequency, and it still is showing a bad SWR, but not bad enough to always fault.

73 Jeff kb2m

-----Original Message-----
From: Don Wilhelm [mailto:[hidden email]]
Sent: Saturday, June 2, 2018 1:54 PM
To: jeff griffin; [hidden email]
Subject: Re: [Elecraft] KPA500 and K3 SWR meters disagree

Jeff,

Check the coax between the KPA500 and the KAT500. Make certain the
connectors are tight. Replace with a different coax if you have one.

You can always do a check on the KPA500 wattmeter by connecting a dummy
load to the KPA500 (no tuner).

73,
Don W3FPR

On 6/2/2018 11:48 AM, jeff griffin wrote:

Jeff Griffin

Re: KPA500 and K3 SWR meters disagree

In reply to this post by Jack Brindle-2

Hi Jack. The swr is so different between the two that there has to be a
problem. I've had this setup for 3 years and never experienced this
behavior.

73 Jedff kb2m

-----Original Message-----
From: Jack Brindle [mailto:[hidden email]]
Sent: Saturday, June 2, 2018 4:47 PM
To: jeff griffin
Cc: [hidden email]
Subject: Re: [Elecraft] KPA500 and K3 SWR meters disagree

Jeff;

Do I understand that for the first test you are driving the antenna through
the KPA500 and KAT500 (with KAT500 in bypass)? If so, it makes a lot of
sense that you will see different SWR. The KPA and KAT are providing a
completely different load for the K3. The better test is to feed the antenna
directly from the K3 without the KPA and KAT in-line. I would expect you to
see a closer match at that point, although I doubt they will ever be
identical due to the differences in the directional couplers in the K3 vs
the KAT500 (and KPA500 for that matter).

Jack, W6FB

> On Jun 2, 2018, at 8:48 AM, jeff griffin <[hidden email]> wrote:
>
> I recently brought my KPA/KAT500 north for the summer and hooked up to my
trapped multiband fan dipole that I use here in NJ. I leave my K3 here for
remote use and use the amp at my winter home in Florida to use with my Flex
6500 with a Steppir Vertical antenna without the KAT500 tuner. When I got up
here I installed the KIO3B option. The install went well with no issues, all
looked good so I connected the K3, P3, KAT500, and KPA500 with the Elecraft
provided cable set like I do every year.
>
> The issue I'm having is an SWR difference between the KAT500 and the K3.
For example if I use the K3's internal tuner I can on a chosen frequency
achieve an SWR of 1/1. I the put the internal K3 tuner in bypass mode and
take the KAT500 out of bypass and set to auto. I then use the xmit button on
the K3 to create a tune signal to be sent to the KAT500. The K3 then shows a
1/1, the KAT500 about the same but the KPA500 which is in STBY mode shows
around 3/1. What this causes to happen is the Amp will fault out if I try to
use any power output. If I check the antenna with a trusted SWR meter I see
1.3/1 at the frequency of use. I upgraded the firmware in all the devices in
use, I also did a reset of the KAT's stored frequencies memory, and checked
both the amp and tuner with the utility programs. I'm going to call Elecraft
on Monday, anyone have any ideas in the meantime I can try?

>
> 73 Jeff kb2m
>
> ______________________________________________________________
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Grant Youngman-2

Re: KPA500 and K3 SWR meters disagree

Have you replaced the coax cable between the KPA500 and the KAT500?

Sent from my iPhone

> On Jun 2, 2018, at 5:04 PM, jeff griffin <[hidden email]> wrote:
>
> Hi Jack. The swr is so different between the two that there has to be a
> problem. I've had this setup for 3 years and never experienced this
> behavior.
>
> 73 Jedff kb2m
>
> -----Original Message-----
> From: Jack Brindle [mailto:[hidden email]]
> Sent: Saturday, June 2, 2018 4:47 PM
> To: jeff griffin
> Cc: [hidden email]
> Subject: Re: [Elecraft] KPA500 and K3 SWR meters disagree
>
> Jeff;
>
> Do I understand that for the first test you are driving the antenna through
> the KPA500 and KAT500 (with KAT500 in bypass)? If so, it makes a lot of
> sense that you will see different SWR. The KPA and KAT are providing a
> completely different load for the K3. The better test is to feed the antenna
> directly from the K3 without the KPA and KAT in-line. I would expect you to
> see a closer match at that point, although I doubt they will ever be
> identical due to the differences in the directional couplers in the K3 vs
> the KAT500 (and KPA500 for that matter).
>
> Jack, W6FB
>
>
>> On Jun 2, 2018, at 8:48 AM, jeff griffin <[hidden email]> wrote:
>>
>> I recently brought my KPA/KAT500 north for the summer and hooked up to my
> trapped multiband fan dipole that I use here in NJ. I leave my K3 here for
> remote use and use the amp at my winter home in Florida to use with my Flex
> 6500 with a Steppir Vertical antenna without the KAT500 tuner. When I got up
> here I installed the KIO3B option. The install went well with no issues, all
> looked good so I connected the K3, P3, KAT500, and KPA500 with the Elecraft
> provided cable set like I do every year.
>>
>> The issue I'm having is an SWR difference between the KAT500 and the K3.
> For example if I use the K3's internal tuner I can on a chosen frequency
> achieve an SWR of 1/1. I the put the internal K3 tuner in bypass mode and
> take the KAT500 out of bypass and set to auto. I then use the xmit button on
> the K3 to create a tune signal to be sent to the KAT500. The K3 then shows a
> 1/1, the KAT500 about the same but the KPA500 which is in STBY mode shows
> around 3/1. What this causes to happen is the Amp will fault out if I try to
> use any power output. If I check the antenna with a trusted SWR meter I see
> 1.3/1 at the frequency of use. I upgraded the firmware in all the devices in
> use, I also did a reset of the KAT's stored frequencies memory, and checked
> both the amp and tuner with the utility programs. I'm going to call Elecraft
> on Monday, anyone have any ideas in the meantime I can try?
>>
>> 73 Jeff kb2m
>>
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:[hidden email]
>>
>> This list hosted by: http://www.qsl.net
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>> Message delivered to [hidden email]
>
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Clay Autery-2

Re: KPA-1500 Fan Noise

In reply to this post by Don Wilhelm

It is NOT JUST a matter of of getting an HD15 M-->F extension cable
(which can be had in lengths up to 100 feet.

A VGA signal is analog and can be extended to up to 100 feet TOTAL
according to the spec, all things being optimum.

But one MUST look at the signals being sent between the KPA-1500 power
supply and RF deck... Are they analog, digital, a mix?
What are the timing spec requirements? Voltage levels? State
difference, et al... Are there capacitance limitations, et al.

73,

______________________
Clay Autery, KY5G
(318) 518-1389

On 06/02/18 12:56, Don Wilhelm wrote:

> Les,
>
> A VGA extension will NOT do the job. Get a cable with all 15 pins
> connected straight through.
>
> 73,
> Don W3FPR
>
> On 6/2/2018 12:07 PM, Les Peters wrote:
>> Jim I agree with your personal observations. I run some high duty
>> cycle modes so I notice the fans kicking into speed 3 a lot when the
>> PA temp gets to 68-70 degrees. That setting does a good job of
>> reducing the temp and keeping it from climbing past 73 degrees. I've
>> changed my min fan speed threshold from 0 to 1 to also help. As you
>> have pointed out 1 is barely perceptible and this helps to reduce the
>> amount of time that fan speeds are on 2+.
>>
>>
>> I'd like to have more separation between the K3S and the KPA1500 RF
>> deck to further distance any noise but the KPAK3AUX cable is only
>> about five feet long, it would be great if that were more like ten
>> feet. Since the cable pin out is straight thru I would imagine a
>> DB15 VGA M-F extension cable would suffice? That would put the
>> potential fan noise even further away but have the RF deck still
>> plenty close enough to view.
>>
>>
>> Les, N1SV
>>
>> #113
>>
>>> Date: Fri, 1 Jun 2018 23:07:20 -0400
>>>      From: "James F. Boehner MD"
>>>      To: "'Elecraft Reflector'"
>>>      Subject: [Elecraft] KPA-1500 Fan Noise
>>>      Message-ID: <002901d3fa1e$d39e0db0$7ada2910$@yahoo.com
>>> mailto:002901d3fa1e$d39e0db0$7ada2910$@yahoo.com >
>>>      Content-Type: text/plain; charset="utf-8"
>>>
>>>      Just thought I would add a few thoughts as far as the fan noise.
>>>
>>>      I'm not certain a YouTube piece would help, but perhaps
>>> personal observations might.
>>>
>>>      First, via the menu, you can select the minimum fan speed, 0-5.
>>> Of course, the fan speed will go up with the Amp temperature.
>>>
>>>      These are my personal observations:
>>>
>>>      0-Nothing
>>>      1-Barely perceptible
>>>      2-Acceptable fan noise, even for SSB operating. Low pitched whine
>>>      3-The noise and the pitch of the whine is past the acceptable
>>> point. Even a very directional mic will probably pick up the noise.
>>> This is where Noise Cancelling headphones would start to help.
>>>      4-Louder and higher pitched whine
>>>      5-Very loud and higher pitched whine
>>>
>>>      So, the fan noise becomes particularly bothersome on level 3
>>> and above. If you are doing CW and/or Digital, the noise will only
>>> be a factor with the operator. On SSB, the noise will probably be
>>> noticeable on the air. However, the SSB duty cycle may not require
>>> higher fan speeds. Those who have been active in contests will
>>> probably know that answer.
>>>
>>>      Rich, if fan noise is going to be that strong a factor, perhaps
>>> you should be looking at tube amps instead. Personally, if I found
>>> the KPA-1500 fan noise excessive in the future, I would plan on
>>> moving it off my desk or remoting it rather than replacing it. It's
>>> integration with the K3 would be very hard to give up.
>>>
>>>
>>>      ?73 de JIM N2ZZ
>>>      #106
>>>      **************************
>>>
>> ______________________________________________________________
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Chris Codella, W2PA

KPA-1500 Fan Noise - measured (sort of)

In an attempt to quantify this, I installed OSHA's free NIOSH app, which
measures noise, onto my iPhone 7 and tried it out. It's not a
measurement instrument, mind you, so the absolute numbers are highly
questionable. But the relative numbers are interesting. I held the
phone at eye level between me and my computer monitor, about 2 feet from
the amplifiers. Here are the results:

dB measured with NIOSH app, rounded to two significant digits:

46 - for comparison - an Alpha 89 running as normal
48 - KPA1500 at fan level 0 (i.e. PS fans only)
51 - fan level 1 (i.e. center fan plus PS fans)
57 - fan level 2 (all fans on)
64 - fan level 3 (all fans on)
67 - fan level 4 (all fans on)
76 - fan level 5 (all fans on)

Similar to other comments I've read, I find up through level 2 to be
okay. At 3 and above I need headphones or, better still, noise
cancelling ones. My experience thus far is that on SSB in normal
conversation at 1500W it stays at level 0 with an occasional excursion
into level 1 if I'm long winded. In the CW WPX test last weekend,
strictly in S&P mode, it stayed at level 0. Experiments with CQing and
on FT-8 are yet to come and I'm sure will require higher speeds.

73,
Chris, W2PA
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Elecraft mailing list

Re: KPA-1500 Fan Noise - measured (sort of)

Thanks Chris,
I do not think I will buy the current configuration of the KPA-1500 fans. I was seriously doing so...... I would still like to know the model number of the fans.....
Mel, K6KBE

From: "Chris Codella, W2PA" <[hidden email]>
To: [hidden email]
Sent: Saturday, June 2, 2018 4:14 PM
Subject: [Elecraft] KPA-1500 Fan Noise - measured (sort of)

In an attempt to quantify this, I installed OSHA's free NIOSH app, which
measures noise, onto my iPhone 7 and tried it out. It's not a
measurement instrument, mind you, so the absolute numbers are highly
questionable. But the relative numbers are interesting. I held the
phone at eye level between me and my computer monitor, about 2 feet from
the amplifiers. Here are the results:

dB measured with NIOSH app, rounded to two significant digits:

46 - for comparison - an Alpha 89 running as normal
48 - KPA1500 at fan level 0 (i.e. PS fans only)
51 - fan level 1 (i.e. center fan plus PS fans)
57 - fan level 2 (all fans on)
64 - fan level 3 (all fans on)
67 - fan level 4 (all fans on)
76 - fan level 5 (all fans on)

Similar to other comments I've read, I find up through level 2 to be
okay. At 3 and above I need headphones or, better still, noise
cancelling ones. My experience thus far is that on SSB in normal
conversation at 1500W it stays at level 0 with an occasional excursion
into level 1 if I'm long winded. In the CW WPX test last weekend,
strictly in S&P mode, it stayed at level 0. Experiments with CQing and
on FT-8 are yet to come and I'm sure will require higher speeds.

73,
Chris, W2PA
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Bob McGraw - K4TAX

Re: KPA-1500 Fan Noise - measured (sort of)

In reply to this post by Chris Codella, W2PA

Using a Sound Level Meter with A weighted scale, measure the noise at 1
meter in at least 4 different directions.   Preferably done in a "free
field" such that any acoustic reflections are at least 6 meters
distant.    I know it is difficult to make measurement outside on a
piece of equipment such as this.   But with these measurements one will
have some quantitative data to evaluate.   {One side may be noticeably
quieter.   Thus turning the amp 90º could make a difference.

Also, an audio spectrum analysis of the noise would be nice. There may
be certain frequencies related to blade tip speed, or bearing chatter
which can be addressed.

I know Jim, K9YC will have extensive knowledge about this method of
evaluating "noise" and can offer some solid advice.

73

Bob, K4TAX

On 6/2/2018 6:12 PM, Chris Codella, W2PA wrote:

> In an attempt to quantify this, I installed OSHA's free NIOSH app,
> which measures noise, onto my iPhone 7 and tried it out. It's not a
> measurement instrument, mind you, so the absolute numbers are highly
> questionable. But the relative numbers are interesting. I held the
> phone at eye level between me and my computer monitor, about 2 feet
> from the amplifiers. Here are the results:
>
> dB measured with NIOSH app, rounded to two significant digits:
>
> 46 - for comparison - an Alpha 89 running as normal
> 48 - KPA1500 at fan level 0 (i.e. PS fans only)
> 51 - fan level 1 (i.e. center fan plus PS fans)
> 57 - fan level 2 (all fans on)
> 64 - fan level 3 (all fans on)
> 67 - fan level 4 (all fans on)
> 76 - fan level 5 (all fans on)
>
> Similar to other comments I've read, I find up through level 2 to be
> okay. At 3 and above I need headphones or, better still, noise
> cancelling ones. My experience thus far is that on SSB in normal
> conversation at 1500W it stays at level 0 with an occasional excursion
> into level 1 if I'm long winded. In the CW WPX test last weekend,
> strictly in S&P mode, it stayed at level 0. Experiments with CQing and
> on FT-8 are yet to come and I'm sure will require higher speeds.
>
> 73,
> Chris, W2PA
> ______________________________________________________________
> Elecraft mailing list
> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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> Post: mailto:[hidden email]
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
> Message delivered to [hidden email]
>

Michael Walker

Re: KPA-1500 Fan Noise - measured (sort of)

Those numbers are pretty impressive for quiet.

Certainly quieter than a quiet dishwasher unless you really pushing it.

Mike va3mw

On Sat, Jun 2, 2018 at 11:09 PM, Bob McGraw K4TAX <[hidden email]>
wrote:

> Using a Sound Level Meter with A weighted scale, measure the noise at 1
> meter in at least 4 different directions. Preferably done in a "free
> field" such that any acoustic reflections are at least 6 meters distant.
> I know it is difficult to make measurement outside on a piece of equipment
> such as this. But with these measurements one will have some quantitative
> data to evaluate. {One side may be noticeably quieter. Thus turning the
> amp 90º could make a difference.
>
> Also, an audio spectrum analysis of the noise would be nice. There may be
> certain frequencies related to blade tip speed, or bearing chatter which
> can be addressed.
>
> I know Jim, K9YC will have extensive knowledge about this method of
> evaluating "noise" and can offer some solid advice.
>
> 73
>
> Bob, K4TAX
>
>
> On 6/2/2018 6:12 PM, Chris Codella, W2PA wrote:
>
>> In an attempt to quantify this, I installed OSHA's free NIOSH app, which
>> measures noise, onto my iPhone 7 and tried it out. It's not a measurement
>> instrument, mind you, so the absolute numbers are highly questionable. But
>> the relative numbers are interesting. I held the phone at eye level
>> between me and my computer monitor, about 2 feet from the amplifiers. Here
>> are the results:
>>
>> dB measured with NIOSH app, rounded to two significant digits:
>>
>> 46 - for comparison - an Alpha 89 running as normal
>> 48 - KPA1500 at fan level 0 (i.e. PS fans only)
>> 51 - fan level 1 (i.e. center fan plus PS fans)
>> 57 - fan level 2 (all fans on)
>> 64 - fan level 3 (all fans on)
>> 67 - fan level 4 (all fans on)
>> 76 - fan level 5 (all fans on)
>>
>> Similar to other comments I've read, I find up through level 2 to be
>> okay. At 3 and above I need headphones or, better still, noise cancelling
>> ones. My experience thus far is that on SSB in normal conversation at
>> 1500W it stays at level 0 with an occasional excursion into level 1 if I'm
>> long winded. In the CW WPX test last weekend, strictly in S&P mode, it
>> stayed at level 0. Experiments with CQing and on FT-8 are yet to come and
>> I'm sure will require higher speeds.
>>
>> 73,
>> Chris, W2PA
>> ______________________________________________________________
>> Elecraft mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/elecraft
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>>
>>
>
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Eric Swartz - WA6HHQ

Re: KPA-1500 Fan Noise

Administrator

In reply to this post by Les Peters

One quick note: We have shifted up the fan turn on temperatures by about 7 degrees for Fan speed 2 and above in our next KPA1500 s/w release and on newly shipping amps. The release should be available in the next week or two.

As noted by others, setting the minimum RF deck fan speed to 1 (or 2 if desired) also further delays going to higher fan speeds in TX.

Also, since the RF deck is instant on, its OK to turn it off from the front panel when you are mostly listening and tuning the band. (The amp can also be set to power up in operate mode in its menu..)

There are no limitations to turning it on and off frequently. (Of course we recommend letting it cool first before turning it off temporarily when running higher duty TX cycles.)

73,
Eric
elecraft.com
_..._
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Paul Baldock

Re: KPA-1500 Fan Noise

At 09:14 PM 6/2/2018, Eric Swartz - WA6HHQ, Elecraft wrote:

>There are no limitations to turning it on and off frequently. (Of
>course we recommend letting it cool first before turning it off
>temporarily when running higher duty TX cycles.)

I would have thought the software would have kept the fans running
even if you tried turn the amp off, until it had cooled down
sufficiently. That's certainly the way my ACOM 2000 works and many other amps.

- Paul
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